The effective them1 conductivities of SiN
and TbFeCo thin films were masulltd by conparing
the length and width of polarizing mcroscope inage of
them-nagnetically written dormins with those of
calculated isothem for the hilayer structum of
subsh'atdSi3N4/Tb22F ~oC08/SiN3 4. The multing data
we= applied to the quadrillayer shuchrre of substratel
Si3N4/Tb22Fe70Cos/Si3N4/Ala,n d the length of calculated
isotherm was tumed out to agree with that of written
dounin.